Advances in MS have allowed for the rapid, efficient identification of many types of PTMs, particularly those that can be detected by a diagnostic mass shift in a peptide fragment ion (e.g. phosphorylation or ubiquitylation). However, standard MS peptide sequencing software tools treat PTMs as an indivisible mass, and are thus unable to identify more complex PTMs, which contribute multiple fragment ions to the CID spectrum. For instance, due to the branched structure of the modified peptides, many ULM conjugates (including the SUMOs) generate highly complex overlapping fragment ion spectra.
This site is dedicated to SUMmOn, a pattern recognition tool that scans CID spectra for the presence of diagnostic fragment ion series. Importantly, the method described here is applicable to any PTM or chemical modification characterized by the presence of a unique fragment ion pattern.
Citing:If you would like to cite SUMmOn please use the folloing reference:
Patrick G A Pedrioli, Brian Raught, Xiang-Dong Zhang, Richard Rogers, John Aitchison, Michael Matunis and Ruedi Aebersol, "Automated identification of SUMOylation sites using mass spectrometry and SUMmOn pattern recognition software", Nat. Methods , July 2006, Volume 3 No 7, pp533 - 539